Urn Project Garden of Innocence: Part 2

In a previous blog, I tested out a design for an urn to donate to Garden of Innocence (GOI). In the first part I printed a 1/2 scale size urn as a test piece for my design. I also continued to get input from GOI about the design requirements for a baby’s urn.

The Full Size Urn Test Print

The full size octagonal urn took about 20 hours to print both the main box and lid. I did make both parts with a 1 cm thick wall, and even with only 15% infill this ranks as one of the longest prints I have done. I made the walls so thick anticipating that the urn would be buried straight into the ground.

Printing the octagonal urn in white PLA

However I learned from GOI that this urn can be placed inside a concrete vault, so for a second iteration I’ll make the urn with a thinner wall. For the file I’ll release, I will be the 0.5 cm wall thickness version.

When I test fitting the printed lid and box together, it took some sanding on the lid rim to get the two pieces to fit firmly together. I wanted the lid to fit with a friction fit so no glue or screws would be required when this urn is laid to rest.

To check that the internal space would be enough to meet the GOI requirements, I filled 2 sandwich bags with a cup of rice each. These two bags would approximate the 1 cup of baby cremains, blanket, and small stuff animal that GOI includes with the remains.

Testing the size of the urn with 2 bags of rice.

The Good and the Warped

The bags of rice were a great confirmation for the internal space of the urn. I wish I could say the same for the lid.

When I printed the full size lid, the Colorfabb PLA Economy filament did warp around the corners, which translated all the way around the shape of the lid. The corners of the main box also warped, giving me an uneven z-band across the bottom of the urn. If you print an urn, you should use a large brim to hold the corners down firmly while it is printing.

The flange of the lid ended up slightly distorted and smaller than the top of the base it was supposed to fit flush with. I also found out that in the process of fiddling with the lid design in AutoCAD 2014 that the rim became offset along the x and y-axis. This resulted in a noticeable gap between the base and lid of the urn. When I printed the test urns earlier at 0.5 scale, the gap did not show.

Full size urn with gap between the lid and box.

This full size prototype will not go to GOI as it sits. But taking in what I have learned, I am hopeful the next iteration will print better.

Stan Baldwin runs a 3D-PT which is a small 3D printing company started by a science teacher with autism. He has a background in CAD and science education, and believes that 3D printing can be used to help the world. 3D-PT develops products for people with autism and other disabilities. 3D-PT is also developing 3D printable products for education.
3D-PT is online at 3dpt.club
Twitter: @3dfidgets